Device for dressing grinding wheels

ABSTRACT

A device for dressing a grinding wheel with an involute profile has an involute motion produced by a straight-edge rolling on a curved guide. The dressing tool toolholder is attached to a plate sandwiched between and slidable relative to a lower plate pivoted on the curved guide axis and an upper further plate carrying the straight-edge. A radial arm pivoted on said guide axis engages first and second slider blocks connected to the further and toolholder plates respectively such that the tool also describes an involute, but whose base circle radius is variable by radial adjustment of the second block.

United States Patent Bartosek Aug. 20, 1974 DEVICE FOR DRESSING GRINDING WHEELS FOREIGN PATENTS OR APPLICATIONS 253,089 5/1926 Great Britain 1. 125/11 T 966,936 9/1957 Germany 125/11 T Primary ExaminerHarold D. Whitehead Attorney, Agent, or Firm-Toren, McGeady and Stanger [57] ABSTRACT A device for dressing a grinding wheel with an involute profile has an involute motion produced by a straight-edge rolling on a curved guide. The dressing tool toolholder is attached to a plate sandwiched between and slidable relative to a lower plate pivoted on the curved guide axis and an upper further plate carrying the straight-edge. A radial arm pivoted on said guide axis engages first and second slider blocks con- ,nected to the further and toolholder plates respectively such that the tool also describes an involute, but whose base circle radius is variable by radial adjustment of the second block.

5 Claims, 6 Drawing Figures 70d I20 ///0 7 5 4 i\ 1e" fla A r a? 9 a 244 PATENTEDAUGZOISM SHEET 2 OF 2 DEVICE FOR DRESSING GRINDING WHEELS This invention relates to a device for dressing grinding wheels with an involute profile.

A known device for performing this task (German Patent Specification No. 966936) comprises a straightedge joined to the arcuate face of a roller block by a pair of oppositely connected tension tapes to perform a rolling motion over said face. The straight-edge is provided with a laterally projecting element that thus describes an involute curve relative to the roller block axis as the straight-edge rolls on the block. The projecting element engages in a radial guide slot in an arm pivotable about the axis of the roller block and a toolholder for the dressing tool also engages in the radial guide slot of the arm. The toolholder is supported on a block that although able to move parallel to the straight-edge, is adjustably fixed in its spacing from the straight-edge, whereby the toolholder also describes an involute. The base circle radius of the involute thus described is determined by the adjustment of said spacing and for this purpose the straight-edge has a side plate directed radially inwards with respect to the roller block, and having a radial guide slot formed in it in which a carrier is adjustable, said toolholder block being mounted on said carrier.

In such devices, due to the forces transmitted through the dressing tool, usually a dressing diamond, inaccuracies often arise in the dressed profile of the grinding wheel which exceed the tolerances that may be deemed permissible for tooth flank errors on the gears to be ground with the wheel. It is an object of the present invention to provide a device for dressing grinding wheels with an involute profile, but that is substantially less susceptible to deflection under load so that a grinding wheel profile can be suitably dressed, even when heavy contact loads are developed on the dressing tool.

In accordance with the invention the device comprises a curved guide over which a planar follower element is arranged to roll, a first slider element mounted on said planar element thereby being constrained to describe an involute related to the axis of the curved guide, a radial guide pivotable on said axis being slidably engaged by said slider element, a second slider element also engaged in said radial guide being attached to a toolholder for the dressing tool, the relative positions of said slider elements along the radial guide being adjustable, the toolholder being supported on a slide that is mounted on guides on a support member pivotable about the curved guide axis and the planar follower element being carried by further slide that is supported for movement parallel to the toolholder slide and relative to the support member. In a particularly simple and robust arrangement, said further slide has guides on the toolholder slide.

One example of a device according to the invention will be described in detail below, with reference to the accompanying drawings, in which:

FIG. 1 is a front elevation of the device,

FIG. 2 is a longitudinal section in the plane 11-11 of FIG. 1,

FIG. 3 is an elevation in the direction of arrow III of FIG. 2, but with the pivot plate and the slides supported thereon in a tilted position,

FIG. 4 is a plan view, partly sectioned on the line IV-IV in FIG. 2,

FIG. 5 is a detail seen in longitudinal section similar to FIG. 2 and showing a modification of that earlier figure for the dressing of wheels for helical gears, and

FIG. 6 is a partly sectioned plan view in the direction of the arrow VI in FIG. 5.

In the dressing device illustrated, a shaft 2 is journalled on a base 1 by two bearings 2a. Mounted on the shaft 2 between the'two bearings is a pivot plate 3. A toolholder slide 4 is mounted by guides 6 onto the pivot plate and is thereby displaceable parallel to the pivot plate and transversely to the shaft axis. Mounted in turn on guides 7 on the toolholder slide is a straight-edge slide 5 that is thus similarly movable parallel to the direction of movement of the toolholder slide.

A roller block 8 is fixed to the base 1 and two tension tapes 9 connect the block 8 with the straight-edge slide 5, one end of each tape being fixed to an extremity of the roller block and the other end to the remote end of the straight-edge slide, the respective tapes being connected to opposite parts of the block and slide.

Pivotally mounted on the shaft 2 by bearing 2b is an arm 10 having a parallel sided slot 10a directed radially to the shaft, the slot accommodating two slider blocks 11 and 12. Slider block 11 is located on a stud journal 11a on the straight-edge slide 5 and the journal axis is coincident with generative arcuate contact surface on the roller block 8. Slider block 12 is located on a stud journal 12a projecting from a toolholder 13 on which is mounted a dressing diamond 14 having its tip set on the geometric axis of the journal 12a. The toolholder 13 also locates in a slot 15a in a front plate 15 on the toolholder slide 4 and is adjustably fixed at any position along this slot by an adjusting spindle 16. The front plate 15 is a rigid U-form member secured to the toolholder slide 4 to straddle the arm 10 which thereby projects through the aperture 15b between the slide 4 and front plate 15.

The device is driven by a double-acting pressure fluid ram consisting of a piston 17 fixed on a connecting rod 18 attached at both ends to the toolholder slide 4, and a cylinder 19 attached to the pivot plate 3. By admitting pressure oil to the left or right hand end of the cylinder, the toolholder slide can be moved accordingly to the right or the left relative to the pivot plate 3.

When the toolholder slide is urged along the guides 6 in one direction relative to the pivot plate 3, since the front plate 15 and hence also the toolholder 13 are fixed to it, the slider block 12 attached to the toolholder tends to pivot the arm 10 in the same direction. But the arm 10 is also engaged by the slider block 11 mounted on the straight-edge slide 5 and the displacing force therefore causes the straight-edge to roll on the stationary roller block 8. Because of the guides 6, 7, the toolholder slide and the pivot plate 3 rotate in unison with the straight-edge slide 5 while relative sliding occurs because of the constraint offered by the engagement of the block 11 with the arm 10, the resultant displacement being as indicated in FIG. 3.

The motion of the axis of the journal 1 la of the block 11 describes an involute E (FIG. 1) based upon the radius of the roller block 8, because of the connection between the block roller and the slide 5. If the axis of the journal 12a is coincident with that of the journal 11a,

itwill be clear that the tip of the dressing diamond 14 will similarly follow this same involute curve as it dresses the profile of a rotating grinding wheel 20. If the block 12 is set radially inwardly of the block 11, as

is shown in FIG. 1, the dressing diamond tip describes an involute e corresponding to a smaller base circle radius and, conversely, if the diamond 14 were raised by the spindle 16 to a position regularly outwards of the axis on the block 11, the involute described by the diamond tip would then correspond to a base circle of larger radius than that of the roller block 8.

It is to be noted that the toolholder 13 is supported directly upon the toolholder slide 4 and forces transmitted through the dressing diamond thus pass through the slide and the robust guides 6, pivot plate 3, shaft 2 and base 1. The straight-edge 5 and roller block 8 have none of the operating pressure applied to them and there is therefore no tendency for deformation to arise causing inaccuracies, even when heavy dressing forces occur.

If the grinding wheel is to be dressed for grinding a helical involute gear, the modified toolholder arrangement illustrated in FIGS. 5 and 6 can be used in the device. Toolholder 21 is mounted as before on the front plate 15 and now carries a support plate 22 rotatably adjustable on pin 22a to be set to a required base helix angle [3b. On the support plate 22, perspective slides 23 each carrying a dressing diamond 14 are displaceable, as indicated by the arrows.

What l claim and desire to secure by Letters Patent is:

1. A device for dressing a grinding wheel with an involute profile comprising, in combination, a support member, a pivot mounting including a pivot axis, said pivot mounting having said support member mounted thereon for pivotal motion about said pivot axis, a toolholder slide supported on said support member, guide means operatively interposed between said support member and said toolholder slide maintaining said toolholder slide at a fixed distance radially from said pivot axis but permitting relative movement between said slide and said support member in directions transversely of said pivot axis, a toolholder for supporting thereon a dressing tool adapted to dress said grinding wheel with said involute profile, a further slide supported on said toolholder slide for movement parallel to said toolholder slide and relative to said support member in directions transversely of said pivot axis, a curved roller guide defining a curved guide surface extending concentrically about said pivot axis, follower means between said roller guide and said further slide operative to constrain said further slide to perform a rolling movement about said guide surface, a first slider element secured relative to said further slide thereby being caused to describe an involute path relative to said pivot axis when said further slide is rolled upon said guide surface, a radial guide member interposed between said toolholder slide and said toolholder and mounted upon said pivot mounting for pivotal motion about said pivot axis, said first slider element being slidably engaged relative to said radial guide member for radial motion therealong relative to said pivot axis, a second slider element secured relative to said toolholder and slidably engaged in said radial guide for movement relative thereto radially of said pivot axis, and means for adjusting the position of said second slider element relative to said radial guide and said toolholder slide in directions radially of said pivot axis whereby the shape of said involute profile may be selectively varied by operation of said adjusting means.

2. A device according to claim 1 wherein said toolholder slide is configured to define therethrough an aperture and wherein said radial guide is arranged to project through said aperture at a position between said guide means and said toolholder.

3. A device according to claim 1 wherein said first slider element is configured as a parallel-sided block, including opposite sides thereof arranged in spaced contact with opposed faces of said radial guide, with a pivot mounting being provided to connect said first slide element relative to said further slide.

4. A device according to claim 1 including motive drive means acting between said toolholder slide and said support member to drive said toolholder slide for movement relative to said support member in directions transversely of said pivot axis thereby to provide motive power for operating said device.

5. A device according to claim 1 including a tool mounting supported on said toolholder and adjustment means for permitting variation of the angular position of said mounting on said toolholder in a plane parallel to the sliding plane of said toolholder slide thereby to permit the device to be used for the dressing of grinding wheels for helical involute gears. 

1. A device for dressing a grinding wheel with an involute profile comprising, in combination, a support member, a pivot mounting including a pivot axis, said pivot mounting having said support member mounted thereon for pivotal motion about said pivot axis, a toolholder slide supported on said support member, guide means operatively interposed between said support member and said toolholder slide maintaining said toolholder slide at a fixed distance radially from said pivot axis but permitting relative movement between said slide and said support member in directions transversely of said pivot axis, a toolholder for supporting thereon a dressing tool adapted to dress said grinding wheel with said involute profile, a further slide supported on said toolholder slide for movement parallel to said toolholder slide and relative to said support member in directions transversely of said pivot axis, a curved roller guide defining a curved guide surface extending concentrically about said pivot axis, follower means between said roller guide and said further slide operative to constrain said further slide to perform a rolling movement about said guide surface, a first slider element secured relative to said further slide thereby being caused to describe an involute path relative to said pivot axis when said further slide is rolled upon said guide surface, a radial guide member interposed between said toolholder slide and said toolholder and mounted upon said pivot mounting for pivotal motion about said pivot axis, said first slider element being slidably engaged relative to said radial guide member for radial motion therealong relative to said pivot axis, a second slider element secured relative to said toolholder and slidably engaged in said radial guide for movement relative thereto radially of said pivot axis, and means for adjusting the position of said second slider element relative to said radial guide and said toolholder slide in directions radially of said pivot axis whereby the shape of said involute profile may be selectively varied by operation of said adjusting means.
 2. A device according to claim 1 wherein said toolholder slide is configured to define therethrough an aperture and wherein said radial guide is arranged to project through said aperture at a position between said guide means and said toolholder.
 3. A device according to claim 1 wherein said first slider element is configured as a parallel-sided block, including opposite sides thereof arranged in spaceD contact with opposed faces of said radial guide, with a pivot mounting being provided to connect said first slide element relative to said further slide.
 4. A device according to claim 1 including motive drive means acting between said toolholder slide and said support member to drive said toolholder slide for movement relative to said support member in directions transversely of said pivot axis thereby to provide motive power for operating said device.
 5. A device according to claim 1 including a tool mounting supported on said toolholder and adjustment means for permitting variation of the angular position of said mounting on said toolholder in a plane parallel to the sliding plane of said toolholder slide thereby to permit the device to be used for the dressing of grinding wheels for helical involute gears. 